All this palaver on every dock / undock is a right royal PITA. There should
be an easier way to run simultaneous audio outputs. I have no desire to
manually reset the volumes for each individual application.

I will ask, but in the meantime you could try the solution that worked
for me, perhaps? Enable the SPDIF profile permanently and enable the
"virtual device for simultaneous output" check. And in
/etc/pulse/default.pa add the line:

load-module module-alsa-sink device=hw:0,0

This line creates an additional "fixed" sink for your audio output,
and then your "combined" sink will include it automatically.

--
Yours, Mikhail Ramendik

Unless explicitly stated, all opinions in my mail are my own and do
not reflect the views of any organization